Officials fear the number could rise once emergency teams are able to survey devastated areas. More than 26,000 people are said to be trapped on rooftops; many urgently need food and drinking water.

Reporting from Islamabad, Pakistan — As the death toll from this week's flash floods rose to at least 800 Saturday, authorities tried desperately to rescue thousands of stranded villagers and deliver emergency relief to stricken areas.

Update: 5:30 a.m. The Associated Press reports that the death toll from Pakistan floods rose to 1,100 Sunday as rescue workers struggled to save more than 27,000 people still trapped by the raging water.

The rescue effort was aided by a slackening of the monsoon rains that have caused the worst flooding in decades in Khyber-Pakhtoonkhwa province. But as flood waters started to recede, authorities began to understand the full scale of the disaster.

"Aerial monitoring is being conducted, and it has shown that whole villages have washed away, animals have drowned and grain storages have washed away," said Latifur Rehman, spokesman for the Provincial Disaster Management Authority. "The destruction is massive."

The country's hardest-hit region was the northwest province of Khyber Pakhtunkhwa, where provincial Information Minister Mian Iftikhar Hussain said the record-breaking monsoon rains had trapped at least 26,700 people on the roofs of buildings and mud huts.

Hussain said the threat of further flooding had subsided in many areas in the northwest but that authorities were struggling to provide relief to thousands of victims, many of whom were in dire need of food, drinking water and medicine.

"All of the government's attention should be directed at combating this calamity," said Hussain, who reported that at least 800 people had died.

Television footage showed vast tracts of submerged housing and farmland across northwest Pakistan, particularly in the cities of Charsadda and Nowshera, as well as the outskirts of the region's largest city, Peshawar. Helicopters and boats had ferried at least 19,000 people from flooded areas, said army spokesman Maj. Gen. Athar Abbas.

The Pakistani army has deployed 30,000 troops to aid in the rescue effort, Abbas said.

Villagers in the Nowshera region complained they had exhausted their food and drinking water supplies and saw no sign of relief coming.

"The government machinery is seen nowhere," said Serfaraz Khan, whose home in Nowshera was severely damaged. "No food, no shelter. People are getting by on a self-help basis."

Pakistan's National Disaster Management Authority was using 31 helicopters and 150 boats in rescue missions. The United States provided seven helicopters as well as inflatable rescue boats, water filtration units, meal packages and 12 temporary steel bridges, the U.S. Embassy said Saturday.

Although the government was stepping up efforts to provide relief and rescue stranded villagers, officials feared that the death toll could rise once emergency teams were able to survey a wider swath of flooded regions.

"The level of devastation is so large that it's possible that in many areas, there are deaths that have not been reported," Abbas said.

Peshawar, a city of 3 million, and surrounding towns remained cut off from the rest of the country because floodwaters had submerged sections of the Islamabad-Peshawar highway and other main roads. Dozens of bridges across northwest Pakistan have been destroyed in the floods. Pakistan's road link to China, the Karakoram Highway, was also shut down because of flooding.